Frangible valve

ABSTRACT

A frangible valve is disclosed. The frangible valve can include an outer portion operable to form a pressure boundary for a pressure vessel. The frangible valve can also include an inner portion integrally formed with the outer portion and having a central region and a separation region about a perimeter of the central region proximate the outer portion. The separation region can have a thickness less than a thickness of the central region and can be configured to break at a predetermined fluid pressure inside the pressure vessel to vent pressure from the pressure vessel.

BACKGROUND

Highly pressurized gas bottles/vessels contain an immense amount ofpotential energy, and accordingly, there are numerous safety codes inplace affecting their design and transportation. A large percentage ofdevelopment costs are attributable to gaining Department ofTransportation (DOT) approval. The general requirement is“vent-before-burst” in the event a vessel was to undergo incinerationduring a transportation-related fire. There are passive and semi-activemeans to achieve “vent-before-burst.” Some designs use ductile tubing,which is designed to yield under increasing pressure, and not fail in abrittle manner. Other designs employ rupture diaphragms that include amembrane designed to fail at a predetermined differential pressure.Another design utilizes a self-igniting pyrotechnic squib, whichactivates an integral valve to vent a vessel at a temperature well belowburst temperature/pressure of the vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1 is an example illustration of a frangible valve system inaccordance with an embodiment of the present invention.

FIG. 2 is an illustration of a frangible valve of the frangible valvesystem of FIG. 1.

FIG. 3 is an illustration of the frangible valve system of FIG. 1 whenthe frangible valve is opened.

FIG. 4 is an illustration of the frangible valve system of FIG. 1 with aproofing support tool.

FIG. 5 is an example illustration of a frangible valve system inaccordance with another embodiment of the present invention.

FIG. 6 is an illustration of a frangible valve of the frangible valvesystem of FIG. 5.

FIG. 7 is an illustration of the frangible valve system of FIG. 5 whenthe frangible valve is opened.

FIG. 8 is an illustration of the frangible valve system of FIG. 5 with aproofing support tool.

FIGS. 9A and 9B are example illustrations of a frangible valve inaccordance with yet another embodiment of the present invention.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result.

As used herein, “adjacent” refers to the proximity of two structures orelements. Particularly, elements that are identified as being “adjacent”may be either abutting or connected. Such elements may also be near orclose to each other without necessarily contacting each other. The exactdegree of proximity may in some cases depend on the specific context.

An initial overview of technology embodiments is provided below and thenspecific technology embodiments are described in further detail later.This initial summary is intended to aid readers in understanding thetechnology more quickly but is not intended to identify key features oressential features of the technology nor is it intended to limit thescope of the claimed subject matter.

Although previous “vent-before-burst” designs have been serviceable,they do have drawbacks. For example, use of ductile tubing, due to itslower tensile strength, will require use of a thicker walled tubing,thus resulting in increased vessel weight. In addition, numericquantification of ductile material burst designs can be quite complex,adding a layer of uncertainty and doubt when introduced into the DOTapproval process. Vessel proofing can be problematic as well forlow-yield strength materials in that ductile material can balloon anddiaphragms can rupture. Furthermore, self-igniting pyrotechnic squibsare not readily available and can be prohibitively expensive. Thus,there is a need for a “vent-before-burst” vessel design that caninexpensively reduce or maintain a low pressure vessel weight andsimplify DOT approval.

Accordingly, a frangible valve is disclosed that allows the use of highstrength, low ductility material to maintain a low pressure vesselweight. In one aspect, the frangible valve provides a simple “by thenumbers” area/material strength calculation to achieve pressure reliefat a given pressure, thus simplifying justification for DOT approval.The frangible valve can include an outer portion operable to form apressure boundary for a pressure vessel. The frangible valve can alsoinclude an inner portion integrally formed with the outer portion andhaving a central region and a separation region about a perimeter of thecentral region proximate the outer portion. The separation region canhave a thickness less than a thickness of the central region and can beconfigured to break at a predetermined fluid pressure inside thepressure vessel to vent pressure from the pressure vessel.

A frangible valve system is further disclosed. The system can include apressure vessel and a frangible valve. The frangible valve can have anouter portion forming a pressure boundary for the pressure vessel. Thefrangible valve can also have an inner portion integrally formed withthe outer portion and having a central region and a separation regionabout a perimeter of the central region proximate the outer portion. Theseparation region can have a thickness less than a thickness of thecentral region and can be configured to break at a predetermined fluidpressure inside the pressure vessel to vent pressure from the pressurevessel.

One embodiment of a frangible valve system 100 is illustrated in FIG. 1.The system 100 can comprise a frangible valve 101 and a pressure vessel102. As described further herein, the frangible valve 101 can beconfigured to maintain pressurized material within the pressure vessel102 up to a predefined pressure, above which a portion of the frangiblevalve will break, thus “opening” the frangible valve to vent pressurizedmaterial from the pressure vessel 102. Thus, in one aspect, the primaryfunction of the frangible valve 101 can be to provide overpressurerelief. The pressure vessel 102 can include a tank 103, canister, pipe,bottle, or any other type of structure configured to contain apressurized fluid. For example, the pressure vessel 102 can beconfigured as a pre-charged cryogenic gas vessel. The tank 103 can havean opening 104 whereby pressurized contents can exit the tank 103. Thepressure vessel 102 can also include a valve housing 105 that can beconfigured to couple with the tank 103 and support the frangible valve101, such as with a valve seat 106. The valve housing 105 can alsoinclude a fluid port 107 and an outlet port 108, which can facilitatecoupling with a hose, pipe, or other structure to receive pressurizedmaterial from the tank 103 when the frangible valve 101 is open. In oneaspect, the outlet port can facilitate venting to atmosphere in theevent that the frangible valve 101 has opened.

With reference to FIG. 2, and continued reference to FIG. 1, thefrangible valve 101 can have an outer portion 110 that can form apressure boundary for the pressure vessel 102. For example, outerportion 110 and the valve seat 106 can be sealed, such as by welding, tomaintain pressure inside the pressure vessel 102. The frangible valve101 can also include an inner portion 120 integrally formed with theouter portion 110 and having a central region 121 and a separationregion 122 about a perimeter of the central region 121 proximate theouter portion 110. The separation region 122 can be configured to breakat a predetermined fluid pressure inside the pressure vessel 102, thus“opening” the frangible valve 101 to vent pressure from the pressurevessel 102 (as shown in FIG. 3). It should be noted that the frangiblevalve 101 is opened entirely due to fluid pressure differential and notdue to the presence of a structural component in contact with a portionof the valve to mechanically facilitate opening of the valve. Moreover,it should be noted that the outer portion 110 of the frangible valve 101does not move as a result of increasing pressure, as doing so would tendto negate the effects of the increasing pressure that would otherwisecause the separation region to break or fail.

In one aspect, the outer portion 110 can comprise an annularconfiguration. In another aspect, the inner portion 120 can comprise adisk configuration, having a greater thickness in the central region 121than outward toward the separation region 122. For example, as shown inFIG. 2, the separation region 122 can have a thickness 130 less than athickness 131 of the central region 121. The greater thickness of thecentral region 121 can ensure that the central region 121 will notsubstantially deflect under increasing pressure, which may inhibit theseparation region 122 from breaking or failing at the predeterminedpressure. In one aspect, a front or pressure side 132 and/or a back side133 opposite the front or pressure side 132 of the frangible valve canbe configured to form a reduced shear ring, which can be designed tofail or shear at the separation region 122 when pressure force on theinner portion 120 exceeds material strength of the frangible valve 101.This configuration can provide a simple, “by the numbers” inner portionarea/material strength calculation to achieve pressure relief of thepressure vessel 102, which can simplify justification for DOT approval.In addition, because the frangible valve 101 provides a simple,dedicated, highly predictable pressure relief function, the tank 103need not fail in a ductile manner (to vent-before-burst). Thus, tankdesigns can be improved to take advantage of high strength, lowductility material, which can reduce or maintain a low weight of thepressure vessel 102.

In one aspect, the outer portion 110 can be configured to facilitateunobstructed movement of the inner portion 120 upon breakage. Forexample, an inner diameter 134 of the outer portion 110 on the back side133 of the frangible valve 101 can be equal to, or greater than, anouter diameter 135 of the inner portion 120 as defined by features onthe front side 132 of the frangible valve 101. In a particular aspect,the outer portion 110 can further (e.g., in addition to comprising anequal to, or greater inner diameter 134) be configured to include anexpanding taper portion 111 at an angle 136 to facilitate unrestrictedmovement of the inner portion 120 relative to the outer portion 110 oncethe frangible valve 101 has “opened,” which can also facilitate thepassage of pressurized fluid between the inner portion 120 and the outerportion 110 as the fluid escapes the tank 103.

It will be recognized by those skilled in the art that the inner portion120 is not intended to seal against the valve seat 106 upon breakage.Indeed, the inner portion 120 can be configured so as to prevent it frombottoming against the valve seat, thus inhibiting flow through fluidport 107. In one aspect, and although not shown, the frangible valve 101may comprise one or more through holes or fluid passageways formed inthe inner portion 120 to prevent blockage of fluid flow through fluidport 107, which through holes or fluid passageways can be similar infunction to the fluid passageway 228 discussed below and shown in FIG.7.

In one aspect, as illustrated in FIG. 4, the system 100 can include aproofing support tool 140 that can be utilized whenever it is desirableto prevent the frangible valve 101 from opening, such as during proof orpressure testing the pressure vessel 102. The proofing support tool 140can be configured to support or shore up the inner portion 120 of thefrangible valve 101 and prevent the inner portion 120 from moving inorder to prevent yielding or breakage of the separation region 122 whenthe pressure in the pressure vessel 102 is greater than thepredetermined fluid pressure, which would otherwise cause the separationregion 122 to break or fail. For example, the proofing support tool 140can include an extension portion 141 configured to extend through theoutlet port 108 to support the inner portion 120, and to exert apressure or force on the backside 133 of the frangible valve 101. In oneaspect, the proofing support tool 140 can be configured to have athreaded engagement with the outlet port 108, although the proofingsupport tool 140 can be coupled with the valve housing 105 or otherwisesupported in any suitable manner. The use of the proofing support tool140 can greatly simplify proofing procedures and remove any pre-yieldquestions pertaining to proofing or autofrettage in the case ofcomposite overwrapped vessels, which is a metal fabrication techniquethat subjects a pressure vessel to enormous pressure, causing internalportions of the part to yield and results in internal compressiveresidual stresses.

In an alternative embodiment, rather than a mechanical solution asprovided by the proofing support tool 140, it is contemplated that fluidor gas pressure from a pressurized source can be used to provide theappropriate pressure to the inner portion 120 of the frangible valve 101in a similar manner as provided by the proofing support tool 140. Such afluid or gas solution is illustrated in FIG. 1. Specifically, apressurized gas or fluid source 142 can be configured to supply a gas orfluid and a corresponding pressure 144 to the back side 133 of thefrangible valve 101, as depicted by the arrows opposing the pressure inthe pressure vessel 102.

FIG. 5 illustrates a frangible valve system 200, in accordance withanother example of the present disclosure. The system 200 can beconfigured as a dual purpose or dual acting valve system. For example,as described further below, the frangible valve system 200 can beconfigured to open via active and passive mechanisms, and includesseparate and distinct features and structures that facilitate thedifferent valve opening mechanisms. The frangible valve system 200 hassome similarities to the frangible valve system 100 of FIG. 1. Forexample, the system 200 can include a frangible valve 201 and a pressurevessel 202, which can include a tank 203 and a valve housing 205.

In addition, with reference to FIG. 6, and continued reference to FIG.5, the frangible valve 201 includes an outer portion 210 and an innerportion 220. In this case, the inner portion 220 comprises a stem 223extending from a side 233 opposite a pressure side 232 of the frangiblevalve 201 and a hole 224 extending partially into the stem 223 from thepressure side 232, which can be used to actively open the valve 201. Thestem 223 can be configured to reside in a fluid port 209 that is influid communication with the channel 251 and an outlet port 208, in thiscase via fluid port 207. At a free end 236 of the stem 223 is afrangible tip 225 configured to break from an external force tomechanically open the frangible valve 201 by exposing the hole 224, thusreleasing fluid from the pressure vessel 202. In one aspect, at least aportion of the stem 223 can be configured to contact a side of the fluidport 209 when acted on by the external force to react the force andfacilitate breakage of the frangible tip 225. The frangible tip 225 canbe broken in any suitable manner. For example, a ram 250 can be movablewithin a channel 251, which can be formed in the valve housing 205 andconfigured to provide the external force to break the frangible tip ofthe stem. The ram 250 can be caused to move by a pyrotechnic charge 252.In one aspect, the frangible tip 225 can include a reducedcross-sectional area portion 226 to facilitate breakage of the frangibletip 225 in a predetermined manner (i.e., to provide a specificallydefined breakage point). The reduced cross-sectional area portion 226can include a portion of the hole 224 to ensure that the hole 224 isexposed upon breaking the frangible tip 225. Thus, to actively open thefrangible valve 201, the pyrotechnic charge 252 can be activated tocause the ram 250 to move in the channel 251 to break the frangible tip225 and expose the hole 224.

Although it is possible to configure the pyrotechnic charge 252 toself-ignite upon reaching a predetermined temperature to preventoverpressure of the tank 203, the frangible valve 201 also includesfeatures that provide passive overpressure protection, thus obviatingthe need for a self-igniting pyrotechnic charge during transport, forexample. For example, as shown in FIG. 6, the inner portion 220 of thefrangible valve 201 includes a separation region 222 configured to breakat a predetermined fluid pressure inside the pressure vessel 202, asdisclosed herein. Thus, the frangible valve 201 can be configured topassively open entirely due to the increasing fluid pressure inside thepressure vessel 202, without a structural component contacting the valveto facilitate mechanically opening the valve. The frangible valve 201can therefore provide “vent-before-burst” functionality for a valve thatis configured to be actively opened by some other means or mechanism,such as the ram 250 moved by the pyrotechnic charge 252.

The stem 223 can be configured to facilitate venting of pressure fromthe pressure vessel 202 once the separation region 222 has broken orfailed, causing the inner portion 220 and the stem 223 to move away fromthe tank 203, as shown in FIG. 7. For example, the stem can comprise anexternally reduced area portion 227 (see FIG. 6) to form a fluidpassageway 228 about the exterior of the stem. Thus, once opened,pressurized fluid can move through the fluid port 209 via the passageway228 about an exterior of the stem 223 to the channel 251 and the outletport 208. The frangible tip 225 and/or the back side of the innerportion 220 proximate the base of the stem 223 can limit the travel ormotion of the “broken” or movable portion of the frangible valve 201. Asshown in FIG. 7, the frangible tip 225 is in contact with a wall of thechannel 251 to limit travel.

In one aspect, as illustrated in FIG. 8, the system 200 can include aproofing support tool 240 configured to support the inner portion 220,via the free end 229 or frangible tip 225 of the stem 223, to preventbreakage of the separation region 222 when pressure testing the pressurevessel 202 to a pressure greater than the predetermined fluid pressure.For example, the proofing support tool 240 can include an extensionportion 241 configured to extend through the outlet port 208 and intothe channel 251 to support the free end 229 or frangible tip 225 of thestem 223.

FIGS. 9A and 9B illustrate a frangible valve 301 in accordance withanother example of the present disclosure. The frangible valve 301 issimilar to the frangible valve 201 of FIG. 6 in many respects. Forexample, the frangible valve 301 includes an outer portion 310, an innerportion 320, and a stem 323 configured to extend from a side opposite apressure side of the frangible valve 301 that includes an externallyreduced area portion to form a fluid passageway about the exterior ofthe stem 323. In this case, the externally reduced area portioncomprises a reduced area portion 360 about a base of the stem 323 and areduced area portion 361 of a frangible tip 325, as well as a reducedarea portion 362 on a main shaft portion of the stem 323. The reducedarea portion 360 about the base of the stem 323 can form a fluidpassageway about a circumference of the stem 323 as the fluid passesaround the inner portion 320 when the valve 301 has been opened. Thereduced area portions 361, 362 can form a fluid passageway for the fluidalong the rest of the length of the stem. The reduced area portions 361,362 can be configured as flats, as shown. It is also noted that the stem323 can comprise a plurality of reduced area portions 361, 362, such asopposing flats located on opposite sides of the stem 323. Takentogether, the reduced area portions 360, 361, 362 can provide acontinuous fluid passageway past the valve 301, even when the innerportion 320 and stem 323 have moved due to the pressurized fluid. Itshould be recognized that the reduced area portions 360, 361, 362 can beof any suitable shape or configuration. Portions of the stem 323 thatare not reduced in area can be configured to contact a side of a fluidport when acted on by an external force to react the force andfacilitate breakage of the frangible tip 325.

In accordance with one embodiment of the present invention, a method forfacilitating venting of a pressure vessel at a predetermined pressure isdisclosed. The method can comprise providing a frangible valve, havingan outer portion operable to form a pressure boundary for a pressurevessel, and an inner portion integrally formed with the outer portionand having a central region and a separation region about a perimeter ofthe central region proximate the outer portion. Additionally, the methodcan comprise facilitating breakage of the separation region at apredetermined fluid pressure inside the pressure vessel to vent pressurefrom the pressure vessel, for example, by constructing and/or utilizingthe example devices and systems as discussed herein. It is noted that nospecific order is required in this method, though generally in oneembodiment, these method steps can be carried out sequentially.

In one aspect, of the method, the separation region can have a thicknessless than a thickness of the central region to facilitate breakage. Inanother aspect of the method, the inner portion can comprise a stemextending from a side of the inner portion opposite the pressure vessel,and a hole extending partially into the stem from a pressure vessel sideof the inner portion, and wherein a frangible tip of the stem isconfigured to break from an external force to expose the hole to releasefluid from the pressure vessel.

It is to be understood that the embodiments of the invention disclosedare not limited to the particular structures, process steps, ormaterials disclosed herein, but are extended to equivalents thereof aswould be recognized by those ordinarily skilled in the relevant arts. Itshould also be understood that terminology employed herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as de factoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thedescription, numerous specific details are provided, such as examples oflengths, widths, shapes, etc., to provide a thorough understanding ofembodiments of the invention. One skilled in the relevant art willrecognize, however, that the invention can be practiced without one ormore of the specific details, or with other methods, components,materials, etc. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the invention.

While the foregoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A frangible valve, comprising: an outer portionoperable to form a pressure boundary for a pressure vessel; and an innerportion integrally formed with the outer portion and having a centralregion and a separation region about a perimeter of the central regionproximate the outer portion, wherein the separation region has athickness less than a thickness of the central region and is configuredto break at a predetermined fluid pressure inside the pressure vessel tovent pressure from the pressure vessel.
 2. The frangible valve of claim1, wherein the outer portion comprises an annular configuration.
 3. Thefrangible valve of claim 1, wherein the outer portion comprises anexpanding taper portion to facilitate unobstructed movement of the innerportion upon breakage.
 4. The frangible valve of claim 1, wherein aninner diameter of the outer portion on a back side of the frangiblevalve is equal to or greater than a frontal outer diameter of the innerportion to facilitate unobstructed movement of the inner portion uponbreakage.
 5. The frangible valve of claim 1, wherein the inner portioncomprises a stem extending from a side opposite a pressure side of thefrangible valve, and a hole extending partially into the stem from thepressure side, and wherein a frangible tip of the stem is configured tobreak from an external force to expose the hole to release fluid fromthe pressure vessel.
 6. The frangible valve of claim 5, wherein thefrangible tip includes a reduced cross-sectional area portion tofacilitate breakage.
 7. The frangible valve of claim 5, wherein the stemis configured to reside in a fluid port, and is configured to facilitateventing of pressure from the pressure vessel through the fluid portabout an exterior of the stem.
 8. The frangible valve of claim 7,wherein the stem comprises an externally reduced area portion to form afluid passageway about the exterior of the stem.
 9. A frangible valvesystem, comprising: a pressure vessel; and a frangible valve, having anouter portion forming a pressure boundary for the pressure vessel, andan inner portion integrally formed with the outer portion and having acentral region and a separation region about a perimeter of the centralregion proximate the outer portion, wherein the separation region has athickness less than a thickness of the central region and is configuredto break at a predetermined fluid pressure inside the pressure vessel tovent pressure from the pressure vessel.
 10. The system of claim 9,wherein the inner portion comprises a stem extending from a sideopposite a pressure side of the frangible valve, and a hole extendingpartially into the stem from the pressure side, and wherein a frangibletip of the stem is configured to break from an external force to exposethe hole to release fluid from the pressure vessel.
 11. The system ofclaim 10, wherein the frangible tip includes a reduced cross-sectionalarea portion to facilitate breakage.
 12. The system of claim 10, furthercomprising a ram movable within a channel and configured to provide theexternal force to break the frangible tip of the stem.
 13. The system ofclaim 12, wherein the stem is configured to reside in a fluid port thatis in fluid communication with the channel and an outlet port, and isconfigured to facilitate venting of pressure from the pressure vesselthrough the fluid port about an exterior of the stem to the channel andthe outlet port.
 14. The system of claim 13, wherein the stem comprisesan externally reduced area portion to form a fluid passageway about theexterior of the stem.
 15. The system of claim 13, wherein at least aportion of the stem is configured to contact a side of the fluid portwhen acted on by the external force to react the force.
 16. The systemof claim 9, further comprising a proofing support tool configured tosupport the inner portion to prevent breakage of the separation regionwhen pressure testing the pressure vessel to a pressure greater than thepredetermined fluid pressure.
 17. The system of claim 16, wherein theproofing support tool is configured to extend through the outlet portand into the channel to support the inner portion.
 18. A method forfacilitating venting of a pressure vessel at a predetermined pressure,comprising: providing a frangible valve, having an outer portionoperable to form a pressure boundary for a pressure vessel, and an innerportion integrally formed with the outer portion and having a centralregion and a separation region about a perimeter of the central regionproximate the outer portion; and facilitating breakage of the separationregion at a predetermined fluid pressure inside the pressure vessel tovent pressure from the pressure vessel.
 19. The method of claim 18,wherein the separation region has a thickness less than a thickness ofthe central region to facilitate breakage.
 20. The method of claim 18,wherein the inner portion comprises a stem extending from a sideopposite a pressure side of the frangible valve, and a hole extendingpartially into the stem from the pressure side, and wherein a frangibletip of the stem is configured to break from an external force to exposethe hole to release fluid from the pressure vessel.